An optical matrix switch is applied to an optical communication network in which a large quantity of data are transmitted through optical fibers in a high speed whereby an optical output signal from one of input optical fibers each connected to the optical matrix switch can be supplied to a selected one of output optical fibers also connected to the optical matrix switch.
One of conventional optical matrix switches is described in the Optical Fiber Communication Conference Technical Digest WB2 published on Jan. 19, 1987. The optical matrix switch comprises a plural rows of optical switch elements dependent upon the respective number of input and output fibers to be connected thereto. Each of the optical switch elements is provided with two inputs and two outputs wherein an optical signal of one of the two inputs can be supplied to any one of the two outputs so that an optical switching operation is realized. The construction and operation of the optical matrix switch will be described in detail later.
According to the conventional optical matrix switch, however, a size thereof is inevitably large in its longitudinal direction. For instance, where the optical matrix switch is provided with four inputs and four outputs to be called "4.times.4 optical matrix switch", four rows of optical switch elements must be included therein. Therefore, the longitudinal length can not be less than a length as much as four times the longitudinal dimension of an optical switch element.
As a result, a substrate on which the four rows of the optical switch elements are provided must be large in its surface area thereby to increase a fabricating cost thereof.
Accordingly, it is an object of the invention to provide an optical matrix switch in which a size thereof can be smaller in its longitudinal direction.
It is a further object of the invention to provide an optical matrix switch in which a substrate for providing a plural rows of optical switch elements thereon can be smaller to avoid the increase of a fabricating cost thereof.
According to the invention, an optical matrix switch comprises,
inputs of N in number where N is an integer,
outputs of M in number where M is an integer,
1.times.M/2 optical switch means of N in number each including a predetermined number of optical switch elements and having a single input connected to a corresponding one of said inputs of N, and having outputs of M/2 in number,
optical switch groups of N/2 in number, each of said optical switch groups including optical switch elements of M/2 in number, each of said optical switch elements being of a 2.times.2 optical switch element having two inputs and two outputs, and
N/2.times.1 optical switch means of M in number each including a predetermined number of optical switch elements and having a single output connected to a corresponding one of said outputs of M, and having inputs of N/2 in number,
wherein said outputs of M/2 in each of said 1.times.M/2 optical switch means of N are respectively connected to said optical switch elements of M/2 of a corresponding group among said optical switch groups of N/2, and said inputs of N/2 in each of said N/2.times.1 optical switch means of M are respectively connected to optical switch elements each selected from each of said optical switch groups of N/2 whereby an optical signal supplied to any one of said inputs of N is switched to be appeared at a predetermined one of said outputs of M by selecting a predetermined one of optical signal transmitting paths formed through said optical switch groups of N/2 between said 1.times.M/2 optical switch means of N and said N/2.times.1 optical switch means of M in accordance with "BAR" and/or "CROSS" states of corresponding optical switch elements therein.